Mailbox guard



FIG. 1 is a perspective view of a mailbox guard showing my new design;

FIG. 2 is a perspective view of the mailbox guard; the broken line showing of the mailbox and post are for environmental purposes only and form no part of the claim design;

FIG. 3 is a top plan view;

FIG. 4 is a side elevational view; and,

FIG. 5 is a front view thereof. 

The ornamental design for a mailbox guard, as shown and described. 